High Tech High School North Bergen Campus Reviews

Introduction

The FA20D engine was a 2.0-litre horizontally-opposed (or 'boxer') iv-cylinder petrol engine that was manufactured at Subaru's engine plant in Ota, Gunma. The FA20D engine was introduced in the Subaru BRZ and Toyota ZN6 86; for the latter, Toyota initially referred to it as the 4U-GSE before adopting the FA20 name.

Key features of the FA20D engine included it:

• Open deck design (i.e. the space between the cylinder bores at the height of the cylinder block was open up);
• Aluminium alloy cake and cylinder head;
• Double overhead camshafts;
• Four valves per cylinder with variable inlet and exhaust valve timing;
• Direct and port fuel injection systems;
• Compression ratio of 12.5:1; and,
• 7450 rpm redline.

FA20D cake

The FA20D engine had an aluminium alloy block with 86.0 mm bores and an 86.0 mm stroke for a capacity of 1998 cc. Within the cylinder bores, the FA20D engine had cast iron liners.

Cylinder head: camshaft and valves

The FA20D engine had an aluminium alloy cylinder caput with chain-driven double overhead camshafts. The four valves per cylinder – two intake and two exhaust – were actuated by roller rocker arms which had congenital-in needle bearings that reduced the friction that occurred between the camshafts and the roller rocker arms (which actuated the valves). The hydraulic lash adjuster – located at the fulcrum of the roller rocker arm – consisted primarily of a plunger, plunger spring, bank check ball and check ball spring. Through the use of oil pressure level and spring force, the lash adjuster maintained a constant goose egg valve clearance.

Valve timing: D-AVCS

To optimise valve overlap and utilise exhaust pulsation to enhance cylinder filling at high engine speeds, the FA20D engine had variable intake and frazzle valve timing, known as Subaru'due south 'Dual Active Valve Control System' (D-AVCS).

For the FA20D engine, the intake camshaft had a sixty degree range of adjustment (relative to crankshaft angle), while the exhaust camshaft had a 54 caste range. For the FA20D engine,

• Valve overlap ranged from -33 degrees to 89 degrees (a range of 122 degrees);
• Intake duration was 255 degrees; and,
• Exhaust duration was 252 degrees.

The camshaft timing gear assembly contained advance and retard oil passages, besides as a detent oil passage to make intermediate locking possible. Furthermore, a thin cam timing oil control valve associates was installed on the front surface side of the timing chain cover to brand the variable valve timing mechanism more compact. The cam timing oil control valve assembly operated co-ordinate to signals from the ECM, controlling the position of the spool valve and supplying engine oil to the advance hydraulic chamber or retard hydraulic sleeping room of the camshaft timing gear associates.

To change cam timing, the spool valve would be activated past the cam timing oil command valve assembly via a signal from the ECM and move to either the right (to advance timing) or the left (to retard timing). Hydraulic pressure in the advance sleeping room from negative or positive cam torque (for accelerate or retard, respectively) would apply force per unit area to the accelerate/retard hydraulic sleeping accommodation through the advance/retard cheque valve. The rotor vane, which was coupled with the camshaft, would then rotate in the advance/retard management against the rotation of the camshaft timing gear associates – which was driven by the timing concatenation – and advance/retard valve timing. Pressed by hydraulic pressure level from the oil pump, the detent oil passage would become blocked so that it did not operate.

When the engine was stopped, the spool valve was put into an intermediate locking position on the intake side by spring power, and maximum advance state on the exhaust side, to prepare for the next activation.

Intake and throttle

The intake system for the Toyota ZN6 86 and Subaru Z1 BRZ included a 'sound creator', damper and a thin safety tube to transmit intake pulsations to the cabin. When the intake pulsations reached the audio creator, the damper resonated at sure frequencies. Co-ordinate to Toyota, this blueprint enhanced the engine induction noise heard in the cabin, producing a 'linear intake sound' in response to throttle application.

In dissimilarity to a conventional throttle which used accelerator pedal effort to make up one's mind throttle angle, the FA20D engine had electronic throttle control which used the ECM to calculate the optimal throttle valve angle and a throttle command motor to command the angle. Furthermore, the electronically controlled throttle regulated idle speed, traction control, stability control and prowl control functions.

Port and direct injection

The FA20D engine had:

• A directly injection organization which included a high-pressure fuel pump, fuel delivery pipe and fuel injector assembly; and,
• A port injection arrangement which consisted of a fuel suction tube with pump and gauge assembly, fuel piping sub-assembly and fuel injector associates.

Based on inputs from sensors, the ECM controlled the injection volume and timing of each type of fuel injector, according to engine load and engine speed, to optimise the fuel:air mixture for engine conditions. According to Toyota, port and direct injection increased performance across the revolution range compared with a port-only injection engine, increasing power by upwardly to 10 kW and torque by up to 20 Nm.

As per the table below, the injection organization had the post-obit operating conditions:

• Cold start: the port injectors provided a homogeneous air:fuel mixture in the combustion sleeping room, though the mixture around the spark plugs was stratified by compression stroke injection from the direct injectors. Furthermore, ignition timing was retarded to enhance exhaust gas temperatures then that the catalytic converter could accomplish operating temperature more quickly;
• Low engine speeds: port injection and direct injection for a homogenous air:fuel mixture to stabilise combustion, meliorate fuel efficiency and reduce emissions;
• Medium engine speeds and loads: straight injection just to utilise the cooling effect of the fuel evaporating as it entered the combustion chamber to increase intake air volume and charging efficiency; and,
• Loftier engine speeds and loads: port injection and direct injection for loftier fuel menses volume.

The FA20D engine used a hot-wire, slot-in blazon air menses meter to mensurate intake mass – this meter allowed a portion of intake air to menstruum through the detection surface area so that the air mass and flow rate could exist measured straight. The mass air menses meter also had a congenital-in intake air temperature sensor.

The FA20D engine had a compression ratio of 12.5:i.

Ignition

The FA20D engine had a directly ignition system whereby an ignition ringlet with an integrated igniter was used for each cylinder. The spark plug caps, which provided contact to the spark plugs, were integrated with the ignition roll assembly.

The FA20D engine had long-accomplish, iridium-tipped spark plugs which enabled the thickness of the cylinder head sub-assembly that received the spark plugs to be increased. Furthermore, the water jacket could be extended near the combustion sleeping accommodation to enhance cooling performance. The triple ground electrode type iridium-tipped spark plugs had 60,000 mile (96,000 km) maintenance intervals.

The FA20D engine had flat type knock control sensors (not-resonant type) attached to the left and right cylinder blocks.

Exhaust and emissions

The FA20D engine had a 4-two-1 frazzle manifold and dual tailpipe outlets. To reduce emissions, the FA20D engine had a returnless fuel system with evaporative emissions command that prevented fuel vapours created in the fuel tank from beingness released into the temper past catching them in an activated charcoal canister.

Uneven idle and stalling

For the Subaru BRZ and Toyota 86, there have been reports of

• varying idle speed;
• crude idling;
• shuddering; or,
• stalling

that were accompanied by

• the 'check engine' light illuminating; and,
• the ECU issuing fault codes P0016, P0017, P0018 and P0019.

Initially, Subaru and Toyota attributed these symptoms to the VVT-i/AVCS controllers not meeting manufacturing tolerances which caused the ECU to detect an abnormality in the cam actuator duty cycle and restrict the operation of the controller. To fix, Subaru and Toyota developed new software mapping that relaxed the ECU'south tolerances and the VVT-i/AVCS controllers were subsequently manufactured to a 'tighter specification'.

There accept been cases, however, where the vehicle has stalled when coming to remainder and the ECU has issued error codes P0016 or P0017 – these symptoms have been attributed to a faulty cam sprocket which could cause oil pressure level loss. Every bit a event, the hydraulically-controlled camshaft could not respond to ECU signals. If this occurred, the cam sprocket needed to be replaced.

fordmorive.blogspot.com

Source: http://www.australiancar.reviews/Subaru_FA20D_Engine.php

Share this post